Pump-Down Residual Operation - Daikin VRV II RXYQ8MY1K Service Manual

Special Control
3.4

Pump-down Residual Operation

3.4.1 Pump-down Residual Operation in Cooling Operation
If the liquid refrigerant stays in the heat exchanger at the startup of a compressor, this liquid refrigerant enters the
compressor, thus resulting in diluted oil in the compressor and then degraded lubrication performance.
Consequently, in order to recover the refrigerant in the heat exchanger while the compressor stops, the pump-down
residual operation is conducted.
Actuator
Compressor
Outdoor unit fan
Four way valve
Main motorized valve (EV1)
Subcooling motorized valve (EV2)
Hot gas bypass valve (SVP)
Receiver gas discharging valve (SVG)
Non-operating unit liquid pipe stop
valve (SVSL)
Ending conditions
3.4.2 Pump-down Residual Operation in Heating Operation
Actuator
Compressor
Outdoor unit fan
Four way valve
Main motorized valve (EV1)
Subcooling motorized valve (EV2)
Hot gas bypass valve (SVP)
Receiver gas discharging valve (SVG)
Non-operating unit liquid pipe stop
valve (SVSL)
Ending conditions
64
Master unit operation
210 Hz + OFF + OFF
Fan control
OFF
2000 pls
0 pls
ON
OFF
ON
• 5 min.
• Pe<0.49 MPa
or
• Td>110°C
Master unit operation
124 Hz + OFF + OFF
STEP7
ON
0 pls
0 pls
ON
OFF
ON
• 30 sec.
• Pe<0.25 MPa
or
• Td>110°C
Slave unit operation
OFF
OFF
OFF
0 pls
0 pls
OFF
OFF
ON
Slave unit operation
OFF
STEP4
ON
0 pls
0 pls
OFF
OFF
ON
Si39-502A
Function